48 INSECTICIDES AND FUNGICIDES. 



added to the filtrate, and the precipitated zinc and iron washed caref ully, 

 dried, finally transferred to a weighed crucible, and carefully separated 

 from the filter. The filter is burned in another crucible after treat- 

 ment with concentrated nitric acid. The residue is again treated with 

 concentrated nitric acid evaporated to dryness and burned. The other 

 crucible is heated with the Bunsen flame, and the combined residues 

 reported as zinc oxid + ferric oxid. The residue is dissolved by 

 digestion with hydrochloric acid, and potassium hydroxid added till the 

 iron is precipitated and the zinc has gone into solution. The precipi- 

 tate is washed, dissolved in hydrochloric acid, precipitated again with 

 ammonia, and finally washed, dried, burned, and weighed as ferric oxid. 



Composition of Bug Death. 



Per cent. 



Sand 4. 35 



Moisture 73 



Volatile, besides moisture (principally NH 4 C1 and some 



KC1) 3.27 



Lead oxid 1. 93 



Zinc oxid 85. 17 



Ferric oxid . 4. 38 



99. 83 



This compound contains only 3.27 per cent of those constituents 

 which would give it any value as a plant food, so that it would not 

 give very good results in this direction. As to its value as an insecti- 

 cide, it is reported as not having any appreciable effect on bugs when 

 applied at the rate of 4-0 pounds to the acre. When applied at the rate 

 of 100 pounds to the acre it kills the bugs but also burns some of the 

 plant leaves. It is too expensive for general use. a 



VELTHA. 



[Serial No. 19845.] 



Composition of Veltha. 



Per cent. 



Sand 32. 73 



Moisture 27. 00 



Carbon 2. 31 



Sulphur trioxid 19. 90 



Ferrous oxid.. . 17.90 



99.84 



This substance is evidently a sample of partially dehydrated ferrous 

 sulphate mixed with about 35 per cent sand and carbon. The green 

 vitriol is very commonly used as a fungicide, but the other 35 per 

 cent is inert in its action on insects. 



"Sixteenth Annual Report of the Maine Agricultural Experiment Station (1900). 



